Why is the sun yellow?

Sun is made up of gases mainly like hydrogen, helium and small amount of other elements like sulphur, magnesium, carbon, neon, iron, oxygen, nickel, chromium and calcium. Temperature on the surface of sun is approximately 5780K, giving the sun white color but it often appears yellow to us when we look at the sun from the earth because of the atmospheric scattering of light.

When white light coming from the sun towards the earth passes through the atmosphere of the earth, the blue light scatters (which is responsible for the sky to appear blue) and is left with red color light which appears to us as yellow. When sun goes down in the west during sunset more blue light is scattered than normal so sun appears to us more dark say orange or red. So it can be said that when we look the sun from the earth it appears yellowish but if we move to the space, out of the atmosphere than we will surely notice a slight change in the color of sun and its brightness too.

Some people believe that the appearance of sun is only the interpretation of human eye, that the light comes from the sun and strikes our retina visual cortex then starts processing and finally tells brain that the light is yellow in color.

Color is detected by photosensitive cells in our eyes which are known as cones, some animals do not have these cones. So it can be possible that they see this light as somewhat grey but this is not actually proved and we are not sure about it. They have black-white rods in their retina which have the high light sensitivity.

Photos of the sun also show the sun to be yellow, so it’s not a retina effect. It’s the atmospheric filtering.

Stars appear white because they do not emit enough light to cause a reflection of the earths water on the atmosphere (blue), which is what alters the sun’s color to us. As a result, they appear to us either white or if you have a good enough telescope, their actual color, which varies depending upon their temperature.

“Stars appear white because they do not emit enough light to cause a reflection of the earths water on the atmosphere (blue), which is what alters the sun’s color to us. As a result, they appear to us either white or if you have a good enough telescope, their actual color, which varies depending upon their temperature.”

Water has nothing to do with the light scattering that causes the sun to look yellow. It’s an entirely atmospheric effect called Rayleigh Scattering.

The brightest stars in the sky actually do have noticable hues (Betelgeuse and Antares look red, Arcturus looks orange, Capella looks yellow, Sirius looks white, and Rigel looks bluish-white, for example). The faint stars don’t appear colored to the naked eye because they emit too little radiation to stimulate the cones in your retina. They only stimulate the rods (which detect light intensity, not color), which results in a general white appearance.

The 3rd paragraph of Ed Sanville’s explanation doesn’t make sense to me. The stars that are “actually white” still appear white (1) when observed through a telescope with significant light-gathering power and (2) when we look at a photograph of the star. The retinal cones are stimulated under both of these conditions, are they not? Yet the sun appears yellow under both of these conditions, does it not?

By “actually white”, I mean “having a spectrum that appears white to the human eye when observed from outside the Earth’s atmosphere”. Let’s not confuse this discussion by including stars like Arcturus that appear non-white when observed from space. The question is: Does Rayleigh Scattering happen to starlight also, and, if so, why do we not seem to notice the effect of it like we do with sunlight?

“The 3rd paragraph of Ed Sanville’s explanation doesn’t make sense to me. The stars that are “actually white” still appear white (1) when observed through a telescope with significant light-gathering power and (2) when we look at a photograph of the star. The retinal cones are stimulated under both of these conditions, are they not? Yet the sun appears yellow under both of these conditions, does it not? ”

Yes, there are some stars that are “actually white.” The sun is in fact a yellow star, but Rayleigh scattering makes it appear far more yellow from the surface of the Earth than it appears from the vacuum of space. In other words, it looks a lot more yellowish-white from outside the atmosphere.

The blue frequencies of visible light from the sun are scattered by particles in the atmosphere giving the sky its bluish color, especially on a clear day. Thus red and green frequences (plus some orange, yellow and violet) reach our eyes resulting in the perception of a color close to yellow.
This process can be demonstrated with spotlights (or flashlights with color filters). Much to the surprise of many people, a yellow color is produced when you shine a red and green light onto a surface. This is because a combination of signals from red and green cones in our retinas are interpreted by our brains as yellow. If you shine red, green and blue light onto a surface you will see a white color.

Some pretty goofy unscientific answers being posted. Just for the record,.. The sky is not blue because of scatter or reflection of water (ocean). The sky is blue because of excitation of an unstable electron shell in Nitrogen ( the most gas in the atmosphere ). The excitation of this electron jumps from this shell back and forth and the wave length of its jump or excitation just happens to emit itself in the blue spectrum of eletromagnetic radiation. The absorption of light by particles in the atmosphere is responsible for the colors that you see during sunsets. the light at tangent to the earth has to go through much more atmosphere to reach your eyes and hence more particles available to absorb more light.